The present invention relates generally to air filtration systems, and more particularly provides a uniquely configured air filtration system which comprises a plurality of cyclonic particulate pre-separators, each having a material collecting chamber and a barrier type filter element housed therein, and a single filter cleaning system which is supported for selective movement into operative engagement with any one of such separators to clean the barrier filter housed therein. As will be seen, the filtration system of the present invention is particularly well suited for use in dry paint or color coating applications to uniquely provide for more rapid changeover to one or more different paint or coating colors.
In the paint or color coating industry, dry powder applications and heat set systems are replacing wet coating application techniques because of, among other reasons, the elimination of the air polluting effluent discharge inherent in wet paint applications. Powder coating methods are especially well suited to high volume production applications where a single color is relegated to the powder application system.
Problems relative to color intermixing occur when it becomes necessary to introduce a different color powder into a given single color system. These color intermix problems are of particular concern in over-sprayed power reclaim systems which typically collect for re-use approximately 60 to 70% of the total dry powder volume discharged from the powder coating guns.
Conventional powder reclaim systems normally comprise an induced draft air flow system which draws the excess powder from the dry powder coating chamber to a single particulate pre-separator and collector housing upon which a self-cleaning barrier filter system is mounted. With each color change in multiple color applications, the powder reclaim system must be disassembled and cleaned of the previous color prior to the introduction into the system of a different color dry powder. Commonly, the single barrier filter is removed and stored for re-use when its color of powder is used again. Entry must be made into the pre-separator and collection chamber to effectively remove the prior color pigments remaining therein before a new color can be utilized in such chambers. Particularly when it is necessary to frequently change powder colors, it can be seen that this conventional system construction necessitates a considerable amount of downtime between each color change.
As a conventional alternative to this single, cleanable filter housing format, particularly where frequent color changes are necessary, systems having multiple particulate pre-separators and collection chambers, each with its own self-cleaning barrier filter system, have been provided for each color powder likely to be used in the dry coating process. As an example, if the overall dry coating process requires the use of six different colored powders, six separate pre-separator housings and associated filters, each "dedicated" to a particular powder color and having its own filter cleaning system, are required. While significantly reducing the color changeover time, the equipment cost of this type of multiple filter and cleaning system apparatus is significantly greater.
It can be seen from the foregoing that, from the standpoint of both labor and equipment cost reduction, improvement over the conventional methods of providing color changes in the dry powder coating industry would be quite desirable. It is accordingly an object of the present invention to provide such improvement.